CN111847811A - A kind of oil field tank bottom sludge treatment method - Google Patents

Abstract

The invention discloses a method for treating oil sludge at the bottom of an oil field tank, which comprises the steps of sequentially carrying out adjustment treatment, sedimentation treatment, cleaning treatment and centrifugal treatment on the oil sludge at the bottom of the tank, firstly adjusting the oxidation-reduction potential of the oil sludge at the bottom of the oil field tank from a low reduction state to an oxidation state or neutral state, improving the oxidation-reduction potential of the oil sludge at the bottom of the tank, reducing the adsorption quantity and adsorption strength of soil in the oil sludge on crude oil, improving the separation efficiency of the crude oil and sand grains in the oil sludge at the bottom of the tank, realizing the recovery of the crude oil in the oil sludge at the bottom of the oil field tank and the standard-reaching treatment of the soil by changing the adsorption force of the oil and soil grains, and ensuring that the recovery rate of the crude oil in the.

Description

A kind of oil field tank bottom sludge treatment method

technical field

The invention belongs to the technical field of environmental protection, and is mainly aimed at the standard treatment of oil field tank bottom sludge (after treatment, the crude oil content in the soil is less than 2%).

Background technique

Tank bottom sludge is a kind of waste produced in the oil field production process, mainly composed of water, crude oil, sediment, etc. It is listed in the national hazardous waste list because of its huge environmental pollution risk. At present, the main technologies for treating oil sludge at the bottom of the tank are: 1) high temperature pyrolysis, in the inert environment of 500 ~ 1000 ℃, the organic matter in the oil sludge is degraded into low molecular weight hydrocarbon condensate and non-condensed gas. 2) Incineration, in the incinerator (rotary furnace: 980-1200°C, fluidized bed: 730-760°C), excess air and auxiliary fuel are introduced to completely burn and remove the organic matter in the sludge 3) Surfactant cleaning, the oil in the sludge is emulsified into the cleaning solution with a high concentration of surfactant solution; 4) Extraction method, adding an organic solvent to the sludge by volume to transfer the crude oil from the soil to the solvent , and then separate the solvent from the soil; but the above methods all have shortcomings, high temperature pyrolysis and incineration have high energy consumption, high processing costs, and cannot recover valuable crude oil, especially tank bottom sludge with high water content is not suitable Using this method; the surfactant cleaning technology needs to add a large amount of surfactant, usually the biodegradability of the surfactant is weak, which brings a lot of problems such as the treatment of a large number of oily sewage; the extraction method needs to add a large amount of organic solvent, the cost High solvent recovery rate and low solvent recovery rate will also bring the risk of environmental pollution in the operating area; therefore, the development of low-cost, high-efficiency and resource-recoverable crude oil processing technologies has always been the focus of close attention in oilfield production.

SUMMARY OF THE INVENTION

The purpose of the present invention is to aim at the technical problems existing in the treatment process of existing oil field tank bottom sludge, and to provide a method for treating oil field tank bottom sludge. Transform into an oxidized state or neutrality, increase the redox potential of the sludge, reduce the amount and strength of adsorption of crude oil by the soil in the sludge, improve the separation efficiency of crude oil and sand particles in the sludge at the bottom of the tank, and reduce the amount of crude oil in the sludge at the bottom of the tank. It has high recovery efficiency and complete crude oil recovery, which reduces the disposal cost of waste tank bottom sludge and the cost of recovering crude oil from waste.

In order to achieve the purpose of the present invention, one aspect of the present invention provides a method for treating oilfield tank bottom sludge, which includes sequentially performing oxidation-reduction potential adjustment, sedimentation, cleaning and centrifugation on the tank bottom sludge.

Wherein, the treatment method is to use the tank bottom sludge treatment equipment to sequentially perform the oxidation-reduction potential adjustment treatment, sedimentation treatment, cleaning treatment and centrifugal treatment on the oil field tank bottom sludge, wherein the treatment equipment includes serially connected through pipelines. Potential adjustment device, sedimentation tank, cleaning device and centrifuge, the potential adjustment device adjusts and increases the redox potential of the oil sludge at the bottom of the tank introduced into the potential adjustment device to obtain the potential adjustment oil mud; , solid-liquid separation to obtain the crude oil floating in the upper part and the sedimentation mud deposited in the lower part; the cleaning device cleans the sedimentation mud to obtain the crude oil floating in the upper part and the mud water mixture settled in the lower part; the mud water mixture enters the centrifuge for centrifugal treatment .

In particular, the potential adjustment device includes a potential adjustment cell, a first mechanical stirrer, a separator, an ORP monitor (ie, a redox potential monitor) and a first fixed beam, wherein: the separator and the ORP monitor are arranged In the potential adjustment tank; the first fixed beam is arranged on the top of the potential adjustment tank; the first mechanical stirrer is fixedly connected with the first fixed beam, and the tank bottom sludge, the potential adjustment oxidant and the water introduced into the potential adjustment tank are Stir treatment.

The first agitator stirs and mixes the sludge, water and oxidant, so that the oxidant and the sludge react fully; the partition plate is used to ensure and avoid the disturbance of the oxidant and the sludge at the bottom of the tank to the ORP monitor; the ORP monitor is used to monitor the sludge Redox potential after sufficient reaction with oxidant.

Wherein, the depth of the cuboid-shaped adjustment pool is not less than 1.5 meters, and the ratio of length to width is 1.5-2:1, preferably 1.5:1.

In particular, the baffle is parallel to the side wall in the width direction of the adjustment tank, and the two sides of the baffle are respectively fixed with the two side walls in the length direction of the adjustment tank, and the height of the baffle is less than the depth of the adjustment tank.

In particular, the upper end of the baffle is flush with the upper end of the adjustment tank, and the lower end of the baffle is 300-800 mm away from the bottom of the adjustment tank, preferably 500 mm.

In particular, the upper part of the side wall of the potential adjustment tank is provided with an introduction port, and the introduction port is connected with the introduction pipe, and the tank bottom sludge, the potential adjustment agent and water are added into the adjustment tank.

In particular, a mud discharge port is provided in the middle and upper part of the side wall of the potential adjustment tank, and the mud discharge port is opened on the side wall on the side opposite to the introduction port. pool.

In particular, the opening height of the mud discharge port is lower than the height of the inlet port; the height difference between the two is 20-100 cm, preferably 50 cm.

In particular, one end of the sludge discharge pipe extends to the lower part of the adjustment tank through the sludge discharge port, and the sludge inlet end of the sludge discharge pipe is 150-200mm away from the bottom of the adjustment tank.

Wherein, the first fixed beam is fixedly installed on the top of the adjustment tank along the length direction or width direction of the adjustment tank, and is located on the center line of the adjustment tank width or length direction, the beam and the width direction side wall or length of the adjustment tank The directional side walls are connected in a fixed connection and fixed to the top of the conditioning pool.

In particular, the distance between the separator and the side wall in the width direction of the adjustment tank close to the partition is 1/4-1/2 of the length of the adjustment tank, preferably 1/4-1/3, more preferably 1/3.

Wherein, the separator is parallel to the side wall in the width direction of the regulating tank, the two sides of the separator are respectively fixed with the side wall in the length direction of the regulating pond, the top of the separator is flush with the top of the potential regulating pond, and the separator is A relatively independent redox potential monitoring area is formed between the baffle and the side wall of the adjustment tank in the width direction close to the baffle.

In particular, the distance between the bottom of the separator and the bottom of the potentiometric adjustment tank is 300-900 mm, preferably 500 mm.

Wherein, the ORP monitor is arranged between the baffle and the side wall of the adjustment tank in the width direction close to the baffle, and the distance between the ORP monitor and the baffle is 100-150mm; the distance between the probes of the ORP monitor The distance from the bottom of the conditioning tank is 600-800mm, preferably 700mm.

In particular, the first mechanical stirrer is arranged in a relatively independent mechanical stirring zone formed between the baffle and the side wall on one side in the width or length direction of the adjustment tank away from the baffle, and the installation position of the first mechanical stirrer is The distance from the side wall on the width direction side of the adjustment tank away from the partition is 1/2-1/4 of the length of the adjustment tank, preferably 1/3-1/4, and more preferably 1/3.

In particular, the installation position of the first mechanical agitator is the same as the distance between the two side walls in the length direction of the adjustment tank.

Wherein, the redox potential adjustment treatment is to add a potential regulator to the tank bottom sludge to adjust the redox potential of the tank bottom sludge to 10mV to 100mV, preferably 15-50mV.

In particular, the potential regulator is selected from percarbonate, persulfate, ozone or ferrate.

In particular, the potential regulator is selected from sodium percarbonate, potassium percarbonate, sodium persulfate, ozone or ferrate, preferably sodium percarbonate, ozone or sodium ferrate.

In particular, in the stirring state, the potential regulator is added to the regulating tank until the oxidation-reduction potential of the sludge at the bottom of the tank reaches 10mV to 100mV, preferably 15-50mV.

In particular, the ratio of the mass of the added potential regulator to the mass of the soil of the tank bottom sludge is (0.5-1.5):100, preferably 1:100.

In particular, the stirring rate is 50-100 rpm, preferably 60 rpm.

In particular, it also includes adding water to the sludge at the bottom of the tank, adjusting the ratio of mud to water, diluting the sludge, reducing the viscosity of the sludge, and facilitating the subsequent separation of oil and soil.

In particular, the ratio of the amount of added water to the mass of the soil in the tank bottom sludge is (4-8):1, preferably (4-6):1, and more preferably 5:1.

Wherein, the settling tank is used for precipitation treatment of the oil mud whose redox potential has been adjusted. Under the action of gravity, solid-liquid separation is performed, and the crude oil after solid-liquid separation is discharged and collected from the upper part of the settling tank; sedimentation after solid-liquid separation The mud is transported to the cleaning tank through the mud discharge pipe.

In particular, the upper part of the side wall of the settling tank is provided with an oil collecting port, the oil collecting port is connected with the oil collecting pipe, and the separated crude oil is discharged from the oil collecting port and collected through the oil collecting pipe; the middle and upper side walls of the settling tank are Set the sludge discharge port of the settling tank, and the sludge discharge port is connected with the sludge discharge pipe to discharge the settled mud in the settling tank.

In particular, the opening height of the mud discharge port on the settling tank is lower than the height of the oil collecting port; the height difference between the two is 30-100 cm, preferably 50 cm.

In particular, one end of the sludge discharge pipe extends to the lower part of the sedimentation tank through the sludge discharge port, and the distance from the sludge inlet end of the sludge discharge pipe to the bottom of the sedimentation tank is 150-200 mm.

In particular, the sedimentation treatment time is ≥30min, preferably 30-45min; the crude oil after the sedimentation treatment is recovered; the sedimentation mud after the sedimentation treatment is cleaned.

Wherein, the cleaning device includes a cleaning tank, a second mechanical stirrer, and a second fixed beam, wherein: the second fixed beam is arranged on the top of the cleaning tank; the second mechanical agitator is fixedly connected to the second fixed beam , and extend into the cleaning tank, and perform stirring treatment on the sedimented mud and chemical degreasing agent introduced into the cleaning tank.

In particular, the cleaning tank has a cylindrical shape, a rectangular parallelepiped shape, a cube shape, and preferably a cylindrical shape.

Wherein, the second fixed beam is fixedly installed on the top of the cleaning tank along the diameter direction of the cleaning tank.

In particular, the second mechanical agitator is installed vertically, and the installation position is located on the center line of the cleaning tank in the height direction.

In particular, the stirring shaft of the second mechanical stirrer coincides with the central axis of the cleaning tank (ie, the central line in the height direction).

In particular, the distance between the bottom of the second agitator and the bottom of the cleaning tank is 100-500mm, preferably 300mm; the ratio of the diameter of the stirring blade of the agitator to the diameter of the cleaning tank is 1:2-5, It is preferably 1:3.

Wherein, the cleaning treatment is to add a chemical degreasing agent to the sedimentation mud after sedimentation treatment to reduce the wettability of crude oil and soil, change the interfacial tension of oil and water, and make crude oil fall off the soil surface under stirring.

In particular, the sedimentation mud is put into the cleaning tank, the second mechanical agitator is turned on, and the chemical degreaser is added under stirring state, and the chemical degreaser reacts with the sedimentation mud to carry out the cleaning treatment.

Wherein, the chemical degreasing agent includes a dispersant and a surfactant, wherein the mass ratio of the dispersant to the surfactant is 1-3:1, preferably 1:1.

In particular, the dispersing agent selects sodium silicate, sodium phosphate or sodium pyrophosphate, preferably sodium silicate; the surfactant selects sodium dodecylbenzenesulfonate (SDBS), alkylphenol polyoxyethylene ether One or more of (OP), petroleum sulfonate (petroleumsulfonate), sorbitan ester (Span), polyoxyethylene ether sorbitan ester (Tween), etc., preferably SDBS.

In particular, the ratio of the added amount of the chemical degreasing agent to the amount of sedimented mud after the sedimentation treatment is less than or equal to 1:100, preferably (0.2-0.5):100.

In particular, the cleaning treatment time is at least 30 minutes, preferably 30-45 minutes.

Wherein, the centrifuge is a horizontal centrifuge, preferably a horizontal screw discharge sedimentation centrifuge.

In particular, mud pumps are respectively arranged on the pipelines connecting the potential adjustment device, the settling tank, the cleaning device and the centrifuge, respectively for pumping the mud in the potential adjusting device to the settling tank, and pumping the mud pump in the settling tank. It is sent to the cleaning device, and the mud in the cleaning device is pumped to the centrifuge.

In particular, the centrifugal speed is 800-1100 rpm during the centrifugation process.

Aiming at the characteristics of high oil content of tank bottom sludge, fine soil particles, low redox potential, and high adsorption strength between crude oil and soil particles, the invention has developed a set of technology based on redox potential adjustment, gravity sedimentation, chemical cleaning, centrifugal separation and the like. The sludge treatment method realizes the rapid separation of crude oil and soil particles, and the recovery and utilization of crude oil.

Compared with the prior art, the present invention has the following advantages:

The tank bottom sludge treatment equipment used in the method of the invention has a simple structure and high treatment efficiency. In the process of using the treatment equipment of the invention to treat the oil field tank bottom sludge, the amount of degreasing agent added in the cleaning tank is small, which reduces the amount of oil removal in the cleaning tank. The concentration of oil agent reduces environmental pollution;

In the process of using a degreaser for cleaning the existing tank bottom sludge, the amount of the degreaser is large, and the concentration of the degreaser to be cleaned is high, usually 3-6%, while the degreaser in the cleaning tank of the present invention is used. The dosage is less than 1%.

The method of the invention firstly adjusts the oxidation potential of the oil sludge at the bottom of the tank, increases the oxidation-reduction potential of the oil sludge, reduces the adsorption amount, adsorption force and adsorption strength of the soil in the oil sludge to the crude oil, so that the crude oil in the oil sludge at the bottom of the tank can easily mix with the soil, The separation of sand particles enables the oil sludge to remove most of the crude oil contained in the oil sludge before chemical cleaning treatment, and improve the separation efficiency of crude oil and sand particles in the oil sludge at the bottom of the tank.

The method of the invention does not need an external heating source in the process of treating the oil field tank bottom sludge, and the power consumption is small;

In the tank bottom sludge treatment process of the invention, it is not necessary to use an organic solvent to extract crude oil, the added amount of chemicals used is small, and the water liquid after the subsequent centrifugal treatment of sludge can be recycled, not only the use cost of chemicals is low, the water consumption is small, but also The crude oil recovery process is simple, which reduces the sludge treatment cost and the crude oil recovery cost;

After the tank bottom sludge is treated by the method of the invention, the crude oil is completely recovered and the recovery efficiency is high. The time is short, the treatment efficiency is high, the soil moisture content after centrifugal dehydration is low, the oil content is low (usually less than 2%), and it can be stacked directly.

Description of drawings

Fig. 1 is the schematic diagram of oil field tank bottom sludge treatment equipment of the present invention;

FIG. 2 is a schematic top view of the structure of the potential adjustment device of the processing equipment of the present invention.

Description of reference numerals

1. Potential adjustment tank; 11. Introduction pipe; 12. Mud discharge pipe; 13. The first mechanical agitator; 14. Baffle plate; 15. ORP monitor; 16. Mud pump; 17. The first fixed beam; 18. Potential monitoring area; 2. Settling tank; 21. Oil collection pipe; 3. Cleaning tank; 31. Second mechanical stirrer; 32. Second fixed beam; 4. Centrifuge; 5. Valve.

Detailed ways

The present invention will be further described below with reference to specific embodiments, and the advantages and characteristics of the present invention will become clearer with the description. However, these examples are only exemplary and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solutions of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "portrait", "horizontal", "top", "bottom", "front", "rear", "left", "right", " The orientations or positional relationships indicated by vertical, horizontal, top, bottom, inside, and outside are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying It is described, rather than indicated or implied, that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

As shown in Figure 1, the treatment equipment for oil field tank bottom sludge of the present invention comprises a potential adjustment device, a settling tank 2, a cleaning device and a centrifuge 4 sequentially connected by connecting pipelines, wherein:

The potential adjustment device is used to improve the oxidation-reduction potential of the sludge at the bottom of the tank, and includes a potential adjustment tank 1, a first mechanical stirrer 13 arranged in the adjustment tank, a partition 14 and an ORP monitor 15 and a first mechanical stirrer 15 arranged on the top of the potential adjustment tank. A fixed beam 17.

A potential regulator is added in the potential adjustment tank, mixed with the sludge, to increase the redox potential of the sludge, and adjust the redox potential of the sludge to 10-100mv (preferably 15-50mv). Oxidant usually selects percarbonate, persulfate, ozone or ferrate, etc., such as sodium percarbonate, potassium percarbonate, sodium persulfate, ozone, sodium ferrate, etc. In the specific embodiment of the present invention, the oxidant takes the above as an example To illustrate, other industrial oxidants that can be used in oil fields are suitable for the present invention, such as calcium hypochlorite, euchloraz, sodium hypochlorite, nitric acid, and the like.

The tank body of the potential adjustment tank is in the shape of a cuboid, the top is open, and the surrounding and bottom are closed. The sludge is converted from a reduced state to an oxidized state, which reduces the adsorption capacity and adsorption strength of the crude oil in the sludge, and improves the separation efficiency of the crude oil and sand particles in the sludge at the bottom of the tank.

In the specific embodiment of the present invention, the length direction of the potential adjustment tank is the left and right directions, the depth direction is the up and down direction, and the width direction is the front and rear direction as an example to illustrate, that is, the two side walls in the width direction of the adjustment tank are the left and right side walls. , the two side walls in the length direction are the front and rear side walls; otherwise, if the width direction of the adjustment pool is used as the left and right method, the length direction is also applicable to the front and rear directions, that is, the two sides of the length direction of the adjustment pool are the left and right side walls, and the width direction The two side walls are the front and rear side walls.

The depth of the potential adjustment tank is not less than 1.5 meters, and the ratio of length to width is 1.5-2:1, preferably 1.5:1.

The upper part of the left side wall of the potential adjustment tank is provided with an introduction port (not shown in the figure), and the introduction port is connected with the introduction pipe 11. The sludge at the bottom of the tank, the oxidant or/and water for adjusting the redox potential are added to the adjustment through the introduction pipe. inside the pool.

The oxidant that adjusts the redox potential of the sludge is input into the potential adjustment tank from the introduction pipe, and mixed with the sludge to increase the redox potential of the sludge; adjust the redox potential of the sludge in the adjustment tank to between 10mV and 100mv; the commonly used oxidants are percarbonate, Persulfate, ozone or ferrate, etc., such as sodium percarbonate, sodium persulfate, ozone, sodium ferrate, etc.

Due to the high solid content or high viscosity of some oil sludge, in order to increase the separation rate of crude oil soil, it is also necessary to add water to the oil sludge in the potential adjustment tank. The ratio of soil solids to water reaches 1:(4-6), and crude oil is rapidly separated from the soil surface.

In the middle and upper part of the right side wall of the adjustment tank, a mud discharge port (not shown in the drawings) is provided on the side wall on the other side opposite to the introduction port, and the mud discharge port is connected with the mud discharge pipe 12, and the mud discharge pipe It extends to the lower part of the adjustment tank through the mud discharge port, and the oil mud after adjusting the redox potential is discharged from the adjustment tank through the mud pump 16, and is transported to the sedimentation tank by the mud pump. The height of the mud discharge port is lower than the height of the inlet port. , the height difference between the two is 20-100cm, preferably 50cm. The sludge discharge pipe extends to the lower part of the adjustment tank through the sludge discharge port, and the sludge inlet end of the sludge discharge pipe is 150-200mm away from the bottom of the adjustment tank.

A first mechanical stirrer 13, a partition plate 14 and an ORP monitor (i.e. a redox potential monitor) 15 are arranged in the potential adjustment tank, and a first fixed beam 17 is arranged on the top of the potential adjustment tank, wherein:

The first fixed beam is fixedly installed on the top of the adjustment tank along the length direction or width direction of the adjustment tank, and is located on the center line of the adjustment tank width or length direction (that is, the distance to the side wall in the width or length direction of the adjustment tank is the same), and the beam It is connected with the left and right side walls or the front and rear side walls of the regulating pool in a fixed connection (eg welding, riveting, bolting, etc.) and fixed on the top of the regulating pool. In the embodiment of the present invention, the first fixed beam is fixedly connected to the left and right side walls of the adjustment tank, and is located on the center line of the adjustment tank in the front-rear direction (ie, the width direction), as shown in Figures 1 and 2 .

The first mechanical stirrer and the first fixed beam are fixed together in a fixed connection, and are vertically arranged in the potential adjustment tank. Oil sludge, oxidant and water are stirred and mixed evenly to make oil sludge with increased redox potential. The setting position of the first mechanical stirrer is close to the left side wall of the adjustment tank, and the distance from the left side wall is 1/3 of the length of the adjustment tank (usually 1/4-1/2, preferably 1/4-1 /3); and is located in the middle of the front and rear directions of the adjustment tank (that is, the same distance between the front and rear side walls of the adjustment tank), as shown in Figures 1 and 2.

The first mechanical agitator selects a propeller-type agitator, a turbine-type agitator, a paddle-type agitator or a ribbon-type agitator, preferably a paddle-type agitator; the ratio of the diameter of the stirring blade of the agitator to the length of the adjustment tank It is (1-3): 9, preferably 2: 9; the distance between the bottom of the stirrer and the bottom of the adjustment pool is 100-300mm, preferably 300mm. The width of the stirring blade is 50mm, and the speed is 60rpm

In the embodiment of the present invention, the stirrer is described by taking a paddle stirrer as an example, and other stirrers used for material mixing in the art are applicable to the present invention, such as a turbine-type or propeller-type agitator.

The partition plate 14 is installed vertically inside the potential adjustment tank, the partition plate is parallel to the left and right side walls of the adjustment tank, and is close to the right side wall of the adjustment tank, and the distance from the right side wall is 1/3 of the length of the adjustment tank (usually 1/4-1/2, preferably 1/4-1/3), and the two sides of the partition are respectively fixed with the front and rear side walls of the adjustment tank, and the top of the partition is connected to the potential adjustment tank The top of the separator is flush, the height of the separator is less than the depth of the adjustment tank, and a relatively independent redox potential monitoring area 18 is formed between the separator and the right side wall, as shown in Figures 1 and 2; sludge, oxidant and water are fully mixed After uniform, enter the redox potential monitoring area from the lower end of the separator to ensure that the oxidant is mixed with the sludge at the bottom of the tank, and at the same time avoid the disturbance of the ORP monitor by the newly added oxidant; the bottom of the separator is far from the potential adjustment pool. The distance to the bottom is 300-900 mm, preferably 500 mm.

The ORP monitor is set in the redox potential monitoring area between the separator and the right side wall of the adjustment tank, and is used to monitor the redox potential of the mixed oil sludge after the sludge and the oxidant have fully reacted, as shown in Figures 1 and 2.

The installation position of the ORP monitor is in the oxidation epoxy potential detection area, and the distance from the partition is 100-150mm; the distance between the probe of the ORP detector and the bottom of the adjustment tank is 600-800mm, preferably 700mm. After the ORP monitor detects that the redox potential of the sludge in the conditioning tank reaches 10-100mV, the obtained conditioning sludge is transported to the settling tank for settlement treatment.

Install a bracket on the side wall of the partition facing the oxidation epoxy potential detection area, the bracket is perpendicular to the partition, the distance from the top of the bracket to the partition is 100-150mm, and the ORP monitor is fixed on the top of the bracket. Install 2-3 brackets on the partition, and fix the ORP detection probe. To facilitate disassembly.

A valve 5 is set on the sludge discharge pipe, which is used to cooperate with the opening or closing of the pump.

As shown in Figure 1, the settling tank 2 is used for precipitation treatment of the oil mud with the adjusted redox potential. The oil mud that is transported to the settling tank by the mud pump is left to stand in the settling tank. Under the action of gravity, the solid-liquid separation, that is, Fine soil particles and oil are separated, and the separated soil settles to the lower part of the sedimentation tank to form sedimentation mud; while the crude oil floats on the upper part.

An oil collecting port (not shown in the figure) is provided on the upper side wall of the settling tank, and the oil collecting port is connected with the oil collecting pipe 21. The separated crude oil is discharged from the oil collecting port and collected through the oil collecting pipe.

The middle and upper side walls of the settling tank are provided with a settling tank sludge discharge port (not shown in the drawings), the sludge discharge port is connected with the sludge discharge pipe 12, and the sludge discharge pipe extends to the bottom of the settling tank through the sludge discharge port, and the settling tank The sludge discharge pipe on the outside is connected with the mud pump, and the settled sludge is discharged from the settling tank through the mud pump, and transported to the cleaning tank 3 through the sludge discharge pipe. The height difference between the two is 30-100 cm, preferably 50 cm. The mud discharge pipe extends to the lower part of the sedimentation tank through the mud discharge port, and the mud inlet end of the mud discharge pipe is 150-200mm away from the bottom of the sedimentation tank.

As shown in FIG. 1, the cleaning device includes a cleaning tank 3, a second mechanical stirrer 31, and a second fixed beam 32, wherein: the second fixed beam is arranged on the top of the cleaning tank; the second mechanical stirrer is connected to the second fixed beam The beam is fixedly connected and extends into the cleaning tank to stir the sedimented mud and chemical degreasing agent introduced into the cleaning tank.

The cleaning tank 3 is in the shape of a cylinder, the top of which is open, the periphery and the bottom are closed, and a chemical degreasing agent is added to the cleaning tank. Crude oil and mud-water mixture that settles in the lower layer.

The cleaning tank can be in any shape, such as a rectangular parallelepiped shape, a cube shape, a cylindrical shape, etc., and a cylindrical shape is used as an example for description in the specific embodiment of the present invention.

A second mechanical agitator 31 is arranged in the cleaning tank, and a second fixed beam 32 is arranged on the top of the cleaning tank, wherein:

The second fixed beam is fixedly installed on the top of the cleaning tank along the diameter direction of the cleaning tank, and the second fixed beam is fixedly connected with the side wall of the cleaning tank (such as welding, riveting, bolting, etc.) and fixed on the cleaning tank the top of.

If the cleaning tank has other shapes, the second fixed beam is arranged on the upper part of the central plane along the height direction of the cleaning tank, such as a rectangular parallelepiped, and the second fixed beam is fixedly installed on the cleaning tank along the length or width direction of the adjustment tank. top, and on the centerline of the tank in the width or length direction.

The second mechanical agitator and the second fixed beam are fixed together in a fixed connection manner, and are vertically arranged in the cleaning tank. The stirring shaft of the agitator is consistent with the height direction of the cleaning tank. (that is, the center line in the height direction) coincides, and the distance between the bottom of the agitator and the bottom of the cleaning tank is 100-500mm, preferably 300mm; the ratio of the diameter of the stirring blade of the agitator to the diameter of the cleaning tank is 1:2 -5, preferably 1:3. The width of the stirring paddle is 50mm, and the speed is 60rpm;

The second mechanical agitator is used to fully mix the active degreasing agent in the added cleaning tank with the sedimentation mud, and to provide hydraulic shear force for the extraction of crude oil contained in the sedimentation mud, so as to improve the separation efficiency of crude oil;

The amount of the chemical degreasing agent added in the cleaning tank and the weight ratio of the settled mud in the cleaning tank are less than 0.5%, preferably 0.2-0.5%.

The chemical degreasing agent includes a dispersant and a surfactant, wherein the dispersant is selected from sodium silicate, sodium phosphate or sodium pyrophosphate, preferably sodium silicate; the surfactant is selected from dodecylbenzenesulfonic acid Sodium (SDBS), alkylphenol polyoxyethylene ether (OP), petroleum sulfonate (petroleum sulfonate), sorbitan ester (Span), polyoxyethylene ether sorbitan ester (Tween), etc. One or more of them, preferably SDBS.

The mass ratio of dispersant to surfactant in the degreasing agent is 1-3:1, preferably 1:1.

The specific implementation of the present invention is only illustrated by taking sodium silicate and dodecylbenzene sulfonic acid as examples, and all degreasers used for chemical cleaning in the art are applicable to the present invention.

The upper side wall of the cleaning tank is provided with an oil collecting port (not shown in the figure), and the oil collecting port is connected with the oil collecting pipe 21. The crude oil cleaned from the sedimentation mud is discharged from the oil collecting port and collected through the oil collecting conduit.

The middle and upper side walls of the cleaning tank are provided with a cleaning tank mud discharge port (not shown in the drawings), the mud discharge port is connected with the mud discharge pipe 12, and the mud discharge pipe extends to the bottom of the cleaning tank through the mud discharge port. The mud discharge pipe on the outside is connected to the mud pump, and the cleaned mud-water mixture is discharged from the cleaning tank through the mud pump, and transported to the centrifuge 4 through the mud discharge pipe. The height of the mud discharge port of the cleaning tank is lower than that of the oil collecting port. The height difference between the two is 30-80 cm, preferably 50 cm. The mud discharge pipe extends to the lower part of the cleaning tank through the mud discharge port, and the mud inlet end of the mud discharge pipe is 150-200mm away from the bottom of the cleaning tank.

The centrifuge 4 performs centrifugal treatment on the mud-water mixture in the lower layer treated by the cleaning tank. Under the action of centrifugal force, the sediment particles with higher density are separated from the water liquid, and the separated water liquid is discharged from the water outlet of the centrifuge. The water is returned to the redox potential adjustment tank through a pump and a return pipe (not shown in the drawings) or is directly discharged; the sediment (sand particles) after centrifugation is discharged from the sludge discharge port of the centrifuge.

In the specific embodiment of the present invention, the centrifuge is a horizontal centrifuge (horizontal screw discharge sedimentation centrifuge, such as Jiangsu Huada Centrifuge Manufacturing Co., Ltd., Wuxi Hengtai Centrifuge Manufacturing Factory, etc.), other centrifuges are suitable in the present invention.

The oil content in the sediment particles discharged from the centrifuge is less than 2%, usually 0.2-1.5%, and the oil removal rate of oil field tank bottom sludge reaches 80-98%, that is, the recovery rate of crude oil in tank bottom sludge is as high as 80- 98%.

The working principle of the oil field tank bottom sludge treatment equipment of the present invention is as follows:

The oil field tank bottom sludge waste, oxidant and/or water are transported into the potential adjustment tank through the introduction pipe of the potential adjustment tank, and the first mechanical agitator is turned on to stir and mix the tank bottom sludge, oxidant (potential adjustment agent) and water, and mix evenly The oil mud enters the redox potential monitoring area from the lower part of the separator, and the ORP monitor monitors the redox potential of the evenly mixed oil mud until the potential of the oil mud is adjusted to 10mV to 100mv, and the oil mud is discharged through the mud pump through the mud pump. The pipe is discharged from the potentiometric adjustment tank to the sedimentation tank;

The oil mud is left standing in the settling tank, and settles for 30-50 minutes under the action of gravity, and the oil and mud are separated. After separation, the crude oil floats on the upper part, and is discharged and collected through the oil collecting pipe through the oil collecting port on the upper part of the settling tank; the soil settles to the point of settling. In the lower part of the tank, sedimentation mud is formed, and under the action of the mud pump, it is discharged from the sedimentation tank to the cleaning tank through the mud discharge pipe; the oil content of the sedimentation mud is 5-65% of the oil content of the oil sludge at the bottom of the tank, that is, the recovery rate of crude oil. 35-95%;

Turn on the second mechanical agitator, and add chemical degreaser to the cleaning tank under stirring state to make the sedimentation mud and degreaser mix evenly. The chemical degreaser reduces the wettability of crude oil and soil and changes the interfacial tension between oil and water. The crude oil falls off the soil surface under the disturbance of stirring; the density difference between the soil particles and the mixed liquid after the crude oil is removed increases, and deposits to the bottom of the cleaning tank under the action of gravity to form a mud-water mixture; the fallen crude oil floats on the bottom of the cleaning tank. The upper part; the fallen crude oil is discharged and collected from the oil collecting port on the upper part of the cleaning tank through the oil collecting pipe; the mud-water mixture settled in the lower part of the cleaning tank is discharged from the situation tank to the centrifuge through the mud discharge pipe under the action of the mud pump;

Turn on the centrifuge, centrifuge the mud-water mixture, and the supernatant water after centrifugation is directly discharged or returned to the potential adjustment tank; the centrifugal sediment is discharged from the mud discharge port of the centrifuge, and the oil content in the centrifugal sediment (sediment) is the tank The oil content of the bottom sludge is 2-20%, and the crude oil recovery rate of the tank bottom sludge after treatment by the treatment equipment of the invention reaches 80-98%.

The composition of the tank bottom sludge separated by the oil field tank bottom sludge treatment equipment of the present invention is as follows:

Oil content 10-60% Water content 20-70%

Solid content 5-60% Soil solid particle size 50-2000um

Redox potential <-100mV

The tank bottom sludge treated by the treatment equipment of the present invention is not limited to the above-mentioned composition, and other oil field tank bottom sludge wastes in the art can be treated by the equipment of the present invention.

In the embodiment of the present invention, the tank bottom sludge in an oil storage tank of an oil field is used as an example for illustration. The average oil content of the tank bottom sludge is 19.5%; the average water content is 49.5%; the average solid content is 31.0%; <1000um; the redox potential of tank bottom sludge is -281.7mV.

Example 1

1. Redox potential adjustment treatment

Add the tank bottom sludge, water and the potential regulator Euchloride into the potential adjustment tank through the introduction pipe of the tank bottom sludge treatment equipment. The mass ratio is 1:100 (usually (0.5-1.5):100), and the ratio of the mass of the water added to the potentiometric adjustment tank to the mass of the soil solids in the tank bottom sludge is 4:1 (usually 4-8 : 1, preferably 4-6: 1), open the first mechanical stirrer, stir, adjust the redox potential of the oil sludge at the bottom of the tank, the mixed mud enters the redox potential monitoring area from the bottom of the clapboard, and the ORP monitor measures The potential of the oil mud is reached and maintained at 42mV, wherein the stirring speed is 60rpm (usually 50-100rpm);

After continuing to stir for 20-40min, the mud pump 16 is turned on, and the mixture (oil mud) after adjusting the potential is transported into the settling tank 2;

2. Settlement treatment

Under the action of the mud pump, the oil mud after the potentiometric adjustment treatment is transported to the sedimentation tank through the mud discharge pipe, and left for 30 minutes (usually the static sedimentation time is at least 30 minutes, preferably 30-45 minutes), under the action of gravity, solid-liquid separation , the fine soil particles are separated from the oil, and the separated oil floats on the upper part of the settling tank, and is discharged and collected from the oil collecting port on the upper part of the settling tank; The sedimentation mud is transported to the cleaning tank; the oil content in the sedimentation mud is 3.6%, that is, the recovery rate of crude oil is 81%, that is, the oil removal rate is 81%;

3. Cleaning treatment

Under the action of the mud pump, the settled mud is transported to the cleaning tank through the mud discharge pipe, and the second mechanical agitator is turned on. Under the stirring state, chemical degreasing agent is added to the settled mud. The degreasing agent includes sodium silicate and SDBS. The ratio of the mass of the degreasing agent to the mass of the settled mud is 0.3:100 (usually (0.2-0.5):100), and the mass ratio of the sodium silicate and SDBS in the degreasing agent The ratio is 1:1 (usually 1-3:1);

After stirring and cleaning for 30 minutes (usually the cleaning treatment time is at least 30 minutes, preferably 30-45 minutes), stop stirring to obtain the upper crude oil and the mud-water mixture deposited in the lower layer. , the sludge-water mixture settled in the lower layer is transported to the centrifuge;

4. Centrifugation

Under the action of the mud pump, the cleaned mud-water mixture is transported to the horizontal screw discharge sedimentation centrifuge (Jiangsu Huada Centrifuge Manufacturing Co., Ltd.) through the mud pipe for centrifugation at a centrifugal speed of 1000 rpm (usually 800 rpm). -1100rpm), the water after centrifugation is discharged or returned to the potentiometric adjustment tank to mix with the oil sludge at the bottom of the tank, the bottom mud soil after centrifugation is discharged, and the oil content of the centrifuged bottom mud soil is 0.8% (that is, the final soil oil content is 0.8% %, less than 2%), the total oil removal rate of oilfield tank bottom sludge reaches 95.8%, that is, the total recovery rate of crude oil is 95.8%.

Example 2

1. Redox potential adjustment treatment

Except that the added potential regulator is sodium persulfate, and the ratio of the mass of sodium persulfate to the solid mass of the tank bottom sludge added in the adjustment tank is 1.5:100, the ORP monitor determines that the potential of the oil sludge reaches and remains within 27mV Otherwise, the rest are the same as in Example 1;

2. Settlement treatment

Except settling for 45min, the oil content in the settled mud is 5.2%, that is, the recovery rate of crude oil is 73.3%, that is, the oil removal rate is 73.3%, the rest are the same as in Example 1;

3. Cleaning treatment

Except that the ratio of the mass of the chemical degreaser to the mass of the settled mud is 0.2:100 (usually (0.2-0.5):100), the mass ratio of sodium silicate to SDBS in the degreaser is 2:1 (usually 1-3: 1), the rest are the same as in Example 1;

4. Centrifugation

Except that the oil content of the bottom sludge after centrifugation is 0.6% (that is, the final soil oil content is 0.6%, less than 1%), the total oil removal rate of the oil field tank bottom sludge reaches 96.9%, that is, the total recovery rate of crude oil is 96.9% Others are the same as in Example 1.

Example 3

1. Redox potential adjustment treatment

Except that the ratio of the mass of sodium ferrate to the mass of the solids of the tank bottom sludge added in the adjustment tank is 0.5:100, and the potential of the sludge measured by the ORP monitor reaches and remains at 15mV, the rest are the same as in Example 1;

2. Settlement treatment

Except settling for 45min, the oil content in the settled mud is 6.9%, that is, the recovery rate of crude oil is 64.6%, that is, the oil removal rate is 64.6%, the rest are the same as in Example 1;

3. Cleaning treatment

Except that the ratio of the mass of the chemical degreasing agent to the mass of the settled mud is 0.5:100 (usually (0.2-0.5):100), the rest are the same as in Example 1;

4. Centrifugation

Except that the oil content in the bottom sludge soil after centrifugation is 1.3% (that is, the final soil oil content is 1.3%, less than 2%), the total oil removal rate of oil field tank bottom sludge reaches 93.3%, that is, the total recovery rate of crude oil is 93.3% Others are the same as in Example 1.

Example 4

1. Redox potential adjustment treatment

Except that the ratio of the mass of potassium ferrate to the mass of the solids of the tank bottom sludge added in the adjustment tank is 1.5:100, and the potential of the sludge measured by the ORP monitor reaches and maintains 50mV, the rest are the same as in Example 1;

2. Settlement treatment

Except that the oil content in the settled mud is 2.9%, that is, the recovery rate of crude oil is 85.1%, that is, the oil removal rate is 85.1%, the rest is the same as that of Example 1;

3. Cleaning treatment

Except for the chemical degreaser including sodium silicate and OP, the ratio of the mass of the chemical degreaser to the mass of the settled mud is 0.35:100 (usually (0.2-0.5):100), and the sodium silicate and OP in the degreaser Except that the mass ratio is 3:1 (usually 1-3:1), the rest are the same as in Example 1;

4. Centrifugation

Except that the oil content of the bottom sludge after centrifugation is 1.1% (that is, the final soil oil content is 1.1%, less than 2%), the total oil removal rate of the oil field tank bottom sludge reaches 94.3%, that is, the total recovery rate of crude oil is 94.3% Others are the same as in Example 1.

The above-mentioned embodiments of the present invention are only exemplary, and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solutions of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

Claims (10)

1. an oil field tank bottom sludge treatment method, is characterized in that, comprises that tank bottom sludge is carried out successively the adjustment processing of oxidation-reduction potential, sedimentation processing, cleaning processing and centrifugal processing. 2 . The method of claim 1 , wherein the redox potential is adjusted by adding a potential regulator to the tank bottom sludge to adjust the redox potential of the tank bottom sludge to 10mV to 100mV. 3 . 3. The method of claim 2, wherein the potential regulator is selected from percarbonate, persulfate, ozone or ferrate. 4. method as claimed in claim 2 is characterized in that, described potential regulator selects sodium percarbonate, ozone or sodium ferrate 5. The method according to any one of claims 1-4, characterized in that, the sedimentation treatment time is ≥ 30min, the crude oil after the sedimentation treatment is recovered; the sedimentation mud after the sedimentation treatment is cleaned. 6. the method as described in any one of claim 1-4 is characterized in that, described cleaning treatment is to add chemical degreasing agent to the sedimentation mud after sedimentation treatment, reduce the wettability of crude oil and soil, change the interface of oil and water Tension, in a state of stirring, the crude oil is released from the soil. 7. The method of claim 6, wherein the chemical degreasing agent comprises a dispersant and a surfactant, wherein the mass ratio of the dispersant to the surfactant is 1-3:1, preferably 1:1. 8. method as claimed in claim 7 is characterized in that, described dispersant selects sodium silicate, sodium carbonate, sodium bicarbonate, sodium phosphate or sodium pyrophosphate, preferably sodium silicate; described surfactant selects One or more of sodium dodecylbenzenesulfonate, alkylphenol polyoxyethylene ether, petroleum sulfonate, sorbitan ester, polyoxyethylene ether sorbitan ester, preferably ten Sodium Dialkylbenzene Sulfonate (SDBS). 9 . The method according to claim 6 , wherein the ratio of the added amount of the chemical degreasing agent to the amount of sedimented mud after the sedimentation treatment is less than or equal to 1:100, preferably (0.2-0.5):100. 10 . 10. The method according to any one of claims 1-4, wherein the centrifugal speed during the centrifugal treatment is 800-1100 rpm.

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